Circuit interrupter



A. P. STROM UPT ER Aug. 2, 1949.

CIRCUIT INTERR 3 Sheets-Sheet 2 Filed Aug. 25, 1944 WITNESSES: flWi 2 INVENTOR F/berf P57 0" BY ;J

& Z ATTORNEY 2 Patented Aug. 2, 1949 CIRCUIT INTERRUPTER Albert P. Strom, Forest Hills, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 25, 1944, Serial No. 551,196

8 Claims.

This invention relates to circuit lnterrupters in general and, more particularly, to arc extinguishing structures therefor.

A general object of my invention is to provide an improved circuit interrupter in which use is made of the arcing pressure to cause a separation of the contact structure and to cause the forcing of an arc extinguishing fluid against the arc to effect the extinction thereof.

Another object is to provide an improved circuit interrupter in which the arcing pressure is utilized to force a wedge member against the contact structure to cause thereby an elongation of the arc.

Another object is to provide an improved circuit interrupter in which the arcing pressure is utilized to assist the operating mechanism in driving the moving parts of the interrupter to their fully open circuit position. Preferably I employ differential piston means to bring about such an improved operation.

Further objects and advantages will readily become apparent upon a reading of the following specification taken in conjunction with the drawings, in which:

Figure 1 is a vertical sectional view through a circuit interrupter embodying my invention and. shown in the closed circuit position;

Fig. 2 is a sectional View taken along the line II-II of Fig. 1;

Fig. 3 is a sectional view taken along the line IIIIII of Fig. 1;

Fig. 4 is a vertical sectional view through a modified type of circuit interrupter embodying my invention;

Fig. 5 is a sectional view taken along the line V-V of Fig. 4

Fig. 6 is a vertical sectional View through a modified form of circuit interrupter embodying my invention; and

Fig. '7 is a sectional view taken along the line VIL-VII of Fig. 6.

Referring to the drawings and particularly to Fig. 1, the reference numeral I designates an insulating arc chamber casing having an insulating cap 2 threadedly secured at 3 to the upper end of the casing I. The cap 2 is threadedly secured at 4 to a metallic piston cylinder 5 in which reciprocates a differential piston 6. Actuating means, in this instance comprising an operating 2 rod 1 are threadedly secured at 8 to the differential piston 6 to initially cause the actuation of the same.

A compression spring 9 disposed between the lower face of the differential piston 5 and the lower and ll) of the cylinder 5 causes a return of the differential piston B to its upper position following a circuit interrupter opening operation. The upward movement of the piston E is halted by stop means in this instance comprising 9. cylindrical portion ll integrally formed with the cap 2. Ports l2 are provided through the cylinder 5 and also through the cylindrical portion l to permit a communication of the arc pressure from the region 13 of the arc chamber through the annular region M to the top surface of the piston 6. Outlet tubes l5 connect the lower end of the cylinder '5 with the region 16 externally of the casing I of the arc chamber. A piston rod I1 is threadedly secured at l8 to the differential piston 6. At the lower end of the piston rod IT is threadedly secured an insulating block member 19 which supports a flat movable wedge member 20 of insulating material. Thus it is apparent that the wedge member 20 is secured to and movable with the rod [1 and the differential piston 6 which move together as a single member. An overpressure valve 2| is provided to limit the pressure within the casing l.

A pair of cooperable contacts 22, 23 are positioned in the lateral walls of the casin l and have respectively secured thereto pistons 24, 25 spring-biased to their inner position by compression springs 25, 21. The pistons 24, 25 operate within piston cylinders 28, 29 which are secured to the casing l by screws 30, more clearly shown in Fig. 3.

Extensions of the contacts 22, 23 have their ends threaded at BI and 32 to cooperate with nuts 33 in supporting in place lugs 39 to which the terminal connections of the interrupter are made. Consequently, in the closed circuit position of the interrupter, as shown in Fig. 1, the electrical circuit therethrough comprises lug 39, contact 22, contact 23 to the other lug 39 to which the other line terminal is connected.

The lower end of the casing l is closed by an insulating plate 40 threadedly secured at ll to the lower end of the casing I. Positioned above the insulating plate 40 are two stacked sets of plate members 42, 43 having their lengths of varying dimensions to form a relatively restricted passage or slot generally designated by the refer ence numeral 44 having corrugated walls into which the insulating wedge plate moves during the opening operation.

A conduit 45 is provided controlled by a valve 45 which leads to suitable means, not shown, which may be employed to permit a flushing flow of oil into the casing I fOllOWi'Iig a circuit interrupter opening operation. During the actual interrupting process when the pressure Within the casing l is relatively high the valve 46 will be closed, thus preventing a flow of fluid through the conduit 45.

The operation of this embodiment of my inven-' tion will now be explained. When it is desired to interrupt the electrical circuit passing through the interrupter, the operating rod 1 is moved downwardly by suitable means, not shown, to cause thereby downward movement of the wedge member 20. The downward movement of the wedge 2i! forces the contacts 22, 23 apart laterally to establish an arc therebetween which is forced by the wedge member 20 to elongate downwardly in the slot 44 adjacent the corrugated wall surfaces thereof. r I

When an arc is established between the contacts 22, 23 it. will react with the oil which completely fills the casing I to generate pressure within the region [3. This pressure generated by the arc acts throughthe conduits 47 to force the pistons 24, 25 further apart to cause thereby a further elongation of the arc. Also the pressure 7 generated, within the region It acts upwardly through the annular passage l4, through the ports I2 and on the upper surface of the differential piston 6 forcing the latter downwardly against the compression sprin 9 and thus assisting the operating mechanism. It is to be noted that the region 48 below the differential piston 5 communicates throughthe tubes 15 to the region l6 which is substantially at atmospheric pressure. The cross sectional area A is the effective piston area upon which the high are pressure acts and is larger than the efiective area a of the movable member which passes through the lower end ID ofthe cylinder ,5 into the region l3. Consequently, there is a differential piston effect which drives the piston 6 and the movable member comprising rod l1 and insulating member '29 downwardly and into the arc chamber against the arc pressure. The overpressure valve 2! limits the pressure attained within the casin I.

During the interruption of very small currentsor during no load operating conditions the operating rod 'lserves to cause downward movement of the wedge member 20. As stated previously during high current interrupting conditions where the pressure within the casing l is relatively high this pressure drives the differential piston 6 downwardly thereby assisting the operating mechanism, not shown, which actuates the operating rod 1.

Following a circuit interrupting opening operation, suitable disconnect means, not shown, may be opened and thus permit a reclosure of the contacts 22, 23, the piston 6 being retracted to its upper position by the operating rod 1. At this time the flushing flow of oil may be forced through the conduit 45, through the valve 65 and into the lower end of the slot 44 to pass upwardly into the casing which forces, if necessary, the valve 21 open to force pontaminated are products out of the casing l. Certain features of the in- 4 terrupting structure herein shown are set forth in U. S. Patent 2,284,347 which was issued to me May 26, 1942, and which was assigned to the assignee of the instant invention.

In the embodiment of my invention shown in Figs. 4 and 5 there is shown a substantially enclosed chamber 55 defined by a metallic cylindrical member 5i and insulating end walls 52, 53 secured by screws 54 to the cylindrical member 5|. A stationary hollow contact 55 is threadedly secured at 53 to the insulating end wall 52.

Cooperable with the hollow contact 55 is a movable contact 5! having a lower guide stem 58 integrally formed therewith. A spider 57a helps in guiding the movable contact 51. A compression spring 59 disposed between the lower end of the movable contact 51 and a plate 69 supported by two upstanding members BI, 52 biases the movable contact 51 to its upper position. A pin 53 passes through the movable contact 51 and cooperates with a pair of crank arms 64 rigidly secured to and movable with an actuating rod 65 which extends through the cylindrical member 5i. Suitable actuating means, not shown, may

cause a rotation of the actuating rod 65 to effect thereby an opening and closing movement of the movable contact 51.

An outlet chamber generally designated by the reference numeral 55 is disposed on the outlet side of the stationary contact 55 being formed by a metallic cylindrical member 59 closed at its upper end by a cap 15 which is secured in place by two studs 7! having their lower ends threadedly secured into the insulating end plate 52. A valve 72 is provided in the cap 10 to control the pressure within the outlet chamber 56. Also preferably a bleeder opening 73 is provided in the cap it; to permit the escape of gas out of the chamber 55 following a circuit interrupter opening operation. An insulating conduit it connects by means of anelbow 15 with an insulating conduit it which communicates at its lower end with a metallic piston chamber 11 within which reciprocally operates a differential piston 78. The upper side of the differential piston F3 is vented through ports T9 to the region externally of the piston chamber T7 and which is substantially at atmospheric pressure.

A retrieving tension spring 8i retrieves the differential piston I8 followin a circuit interrupting opening operation. If desired, a flushing conduit 82 may be provided which is similar in construction to conduit 45 previously described in connection with Fig. 1 and having the same function.

The opening operation of the interrupter will now be explained. To open the electrical circuit passing through the interrupter, suitable means, not shown, causes a rotation of the actuating rod 55 to thereby cause a downward movement of the movable contact El. This establishes an are between the stationaryand movable contacts 55, 5? which generatessubstantial pressure within the chamber 50 as aresult of the arcreacting upon oil in which the chamber 55 is submerged. This pressure acts through the hollow stationary contact 55 throughthe outlet chamber 65 and through the conduits 74-, '16 to drive the differential piston member 18 upwardly, thereby forcing oil into the chamber 55 and against the are drawn between the stationary and movable contacts 55, 51. This extinguishes the arc and the circuit passing between the terminal lugs 83, 84 is thereby interrupted.

'In circuit interrupters designed to open circuits carrying large currents, very powerful springs are required to operate the mechanism. In my invention it is proposed to utilize the energy of the are itself to aid the spring which causes the initial separation of the contacts. Thus the operating force will increase with the current so that the initial operating spring needs to be only sufficiently strong to open contacts during no load operation. In the interrupter shown in Figs. 4 and 5 means could be used for operating the fluid driving piston by gas or spring operating mechanisms tripped simultaneously with the breaker. The operation of such pistons mechanically would require energy in the order of 500 foot pounds which would mean a very cumbersome spring mechanism, as well as somewhat complicated devices for synchronizing the piston with the movement of the movable contact structure.

In the invention herein disclosed the differential piston I9 has a larger diameter at its lower end which operates in the piston chamber 11 of corresponding size. The differential piston I8 has a smaller diameter at its upper end which operates in a piston chamber 85 of correspondingly smaller size. The large end of the differential piston l8 communicates to the outlet chamber 59. The upper small end of the differential piston 19 communicates directly to the chamber 59. The relief valve I2 is located in chamber 69 and may be set to vent at any desired pressure. When the movable contact 51 opens, pressure is immediately created which tends to push differential piston I8 upward. Outlet chamber 653 will remain at a pressure P1 determined by the relief valve 12. P1 will always be equal to or somewhat less than the pressure P2 at the small end of the diiferential piston I8 and in chamber 59. The pressure on the large side of the differential piston 18 will thus always be sufficient to force it up. lhe are drawn between the stationary and movable contacts 55, 51 is then quenched by pressure within chamber 59 which decreases the arc space and forces oil through it. If too much gas is generated the excess will escape through the relief valve I2.

This interrupter successfully interrupted the full range of currents from 150 to 2000 amperes at 13,800 volts, whereas, without the self generated blast, that is with no blast at all, the upper voltage limit is about 4600 volts.

The embodiment of my invention shown in Figs. 6 and 7 will now be explained. Referring more particularly to Fig. 6, the reference numeral 8'! designates an elongated insulating casing threadedly secured at 88 to a cap 89 which is threadedly secured at 90 to a metallic piston chamber 9| within which operates a differential piston 92. A sleeve wedge 93 is threadedly secured at 94 to the differential piston 92 and moves therewith. A U-shaped bracket 95 is secured to the differential piston 92 and is threadedly secured at 96 to an operating rod 91 actuated by suitable mechanism, not shown.

The operating rod 91 is latched in closed circuit position by a latch 98 actuated by a solenoid 99. An accelerating spring I00 biases the differential piston upward toward its fully open circuit position.

The sleeve wedge 93 is adapted to cause a separation between a stationary contact IUI and a movable contact I92 which is spring-biased to its closed position by a compression spring I93. The casing 81, the sleeve wedge 93, and a sleeve I04 which surrounds the stationary contact I BI are preferably made of a gas evolving material such as fiber or boric acid which evolves an are extinguishing gas upon being subjected to an arc. A conduit I05 interconnects the region I06 adjacent the contact structure with the region I01 in back of the differential piston 92. Also there is a direct communication between these regions through the sleeve wedge 93 itself.

In the closed circuit position of the interrupter as shown in Fig. 6, the electrical circuit therethrough comprises terminal lug I09, movable contact I92, stationary contact IIiI to the other terminal lug I99. When it is desired to open the circuit through the interrupter the solenoid 99 is energized to cause an opening movement of the latch 98 which permits the accelerating spring I99 to force the differential piston 92 upwardly to thereby cause the sleeve wedge 93 to effect a separation between the stationary and movable contact IOI, I92 to draw an arc therebetween. The upward movement of the sleeve wedge 93 thus not only causes a separation of the contact structure but elongates the are thereby formed causing an intimate engagement therewith against the walls of the casing 8'! and the sleeve I 94. The gas which is evolved as a result of the interaction between the arc and the gas evolving walls of the casing 81 and IM and wedge 93 acts through the sleeve wedge 93 and also through the conduit I to the back side of the differential piston 92. Since a portion of the upper surface of the differential piston 92 is vented to atmosphere through the ports III the differential piston 92 moves upwardly to continue the upward movement of the sleeve wedge 93 elongating the arc and thereby assisting the accelerating compression spring I99. As disclosed herein, this device is operated in air with the gas generated as a result of using gas evolving materials. However, this device could be readily adapted for use in oil in which case the arc would react 0n the oil itself to produce the desired pressure.

Following an interruption the differential piston remains at its upper position at the up a. end of the piston chamber 9| maintaining the contacts separated. To effect a closure of the electrical circuit through the interrupter suitable means, not shown, may cause a downward movement of the operating rod 91 thereby causing a retracting of the sleeve wedge 93 to effect thereby a reengagement between the stationary and movable contact ItiI, M2. When the differential piston 92 is at its lowermost position as shown in Fig. 6, the latch 98 will then be moved to the right to engage the notch III to thereby latch the breaker in its closed position.

From the foregoing description of a few specific embodiments of my invention it will be apparent that I have provided novel means for utilizin the arc pressure to force fluid toward the arc to effect the extinction thereof. Also I have utilized the arcing pressure to effect movement of wedge members which elongate the arc to facilitate its interruption. By an application of my invention to existing circuit interrupters,

1e spring pressures required in the operating mechanism may be considerably reduced and thus the energy requirements are considerably diminished. Furthermore, the effect of having the arcing pressure assisting the operating mechanism means that during the interruption of high amperage currents there is a corresponding increase in arcing pressure, whereas, in the interruption of low amperage currents where the velocity of the fluid fiow need not be so great, reliance can be had on the relatively small spring pressures used in the operating mechanism.

Although I have shown and described specific embodiments of my invention, it is to be clearly understood that the same were merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter, a casing, a pair -,of separable contacts positioned laterally in the walls of the casing and separable to establish ,an-arc, a piston secured to and movable witheach contact, conduit means connecting one side of each piston to the interior of the casing, a differential piston having a Wedge member secured thereto, actuating means-for initially operating the piston to cause the wedge member to cause a separation of the pair of.-separab1e contacts to establish an arc therebetween, the arcing pressure then causing a further separation of the pair of contacts and also an actuation of the diiferential piston to cause thereby a driving of the wedge member against the arc to cause a furtherelongation of the same.

2. In acircuit interrupter of the fluid type, an elongated tubular insulating casing composed of a gas evolving material, a piston chamber adjoining the tubular casing adjacent one -end thereof, a stationary rod-shaped contact project- 'ing into the tubula gas evolving casing at the other end thereof, a movable contact, means biasing the movable contact laterally against the side of the projecting end of the stationary contact, a differential piston member carrying an elongated sleeve wedge composed of gas evolving material and movable within the piston chamber; means biasing the differential piston member, and sleeve wedge in the direction of causing separation of the contacts, and'conduit means interconnecting the arcing region with the region back of the diiierential piston.

3. In a circuit interrupter of the fluid type, an elongated tubular insulating casing composed of a gas evolving material, a piston chamber adjoining the tubular casing adjacent one end thereof, a stationary rod-shaped contact projecting into the tubular gas evolving casing at the other end thereof, a movable contact, means'biasing the movable contact laterally against the side of the projecting end of the stationary contact, a differential piston member'carrying an elongated sleeve wedge composed of gas evolving inaterial' and movable within the piston chamber, means biasing the differential piston member and sleeve wedge in the direction of causing separationcf thecontacts, conduit means interconnectillg the arcing region with the region baokof the diiierential piston, an operating rod fixedly secured to the difierential pistonv and extending through the end of the piston chamber, and means releasably latching the operating rod to the closed circuit position.

4. In a circuit interrupter of the'fluid type, an

- elongated tubular insulating casing composed of a gas evolving material, a piston chamber adjoining the tubular casing adjacent one end thereof, a stationary rod-shaped contact projecting into the tubular gas evolving casingat the other end thereof, a movable contact, means biasing themovable contact laterally against the side ofthe projecting end of the stationary contest a diilerentia p ston member car n an elongated-sleeve wedge composed pf gas evolving material and movable within the piston chamber, means biasing the differential .piston member and sleeve wedge in the directionof causing separation of the contacts, conduit means intericonnecting the -arcing region with the region back of the differential piston, and the diiierential piston member bein hQllOW-topermita direct communication of the arc gases therethroug h.

:5. In a circuit interrupter o;f theiluid type, an elon ated tubular insu atin casin compo d o a :gasevolving material, a piston Chamber adj oiningthe tubular casing adilcentoneend thereof, a stationary rod-s aped co tact pro ectin i to the tubular gas evolving casing ,at-the other end thereof, a movable contact, means biasing the movable contact laterally againstthe side of the projecting end of the stationarycontact,a-di-fferential piston member carrying an elongated sleeve .wedge composedof gasevolving material and movable within thepiston chamber, vmeans biasing the differential piston member and sleeve wedg in the direction of causing separation of the contacts, and the difterential piston member being hollow to permit a direct connnunication of the arc gases therethrough.

6. In a circuit interruptena substantially-enclosed elongated casing, a stationary contact projecting-into the casing adjacent one end thereof,

passage means permitting communication betweenthe arcingregion and theregion'back of the dlfferential piston member.

'7. In a circuit interrupter, a substantially enclosed elongatedcasing, astationary contact projecting into the casing adjacent one end theerof, a piston chamber adjoining the other end of the casing, a movable contact cooperable withthe stationary contact to drawan arc laterallypf the casing, an elongated sleeve wedge, and flierential piston member movable within the piston chamber and carrying therewith the sleeve wedgerpassage means permitting communication between. the arcing region and the, region ,back of the difierential piston member, means bias- ,ing. the dififerential piston member ,and sleeve wedge to effect are, lengthening, and means releasably latching the pistonmemberin the closed circuit position.

8. In; a circuit interrupter, means forestab- .zlishi-ng an am, an arc chamber confining the ,pressure created by thearc,,means,at least partly ,of insulating material defining ,arelatively restricted passage for receiving the arc, a movable piston movable therein for actuating said .mov-

, able,member, one side of said piston being sub- ;.jec,ted to the pressurecreated by the ar c, m eans venting said cylinder at the other side of said piston to the outside of said are chambensaid piston having an effective piston area ,at said ,oneside-acted upon by the arc-pressure greater ,than the, effective area, of said :mOl able member --.which,is acted,onby the pressure inthearc chamberandasaidpiston ct atinesa dmovabl .-.member to moveit further int th ,.a1. -,B tmher and into said relatively restricted passage Number against the are pressure. 2,020,475 ALBERT P. STROM. 2,077,338 2,993,250 REFERENCES CITED 5 2,147,497

The following references are of record in the file of this patent. 2:236:131 UNITED STATES PATENTS 2,386,611 Number Name Date 10 1,276,675 Merriam Aug. 20, 1918 Wm 1,535,835 Hilliard, Apr. 28, 1925 1,958,362 Fischler May 8, 1934 16 Name Date Ronnberg Nov, 12, 1935 Lingal et a1 Apr. 13, 1937 Ronnberg Sept. 14, 1937 Prince et a1 Feb. 14, 1939 Paul Aug. 19, 1941 Strom May 29, 1942 Wallace et a1. June 9, 1942 Ileman Oct. 9, 1945 FOREIGN PATENTS Country Date Great Britain Dec. 1, 1942 

